1. Field of the Invention
The field of invention relates to an apparatus and method of using petroleum-drilling tools on a drill string. More specifically, the field directs to an apparatus and method of using a dynamically controlled drill string in a well bore.
2. Description of the Related Art
In horizontal drilling, there are many challenges to maintaining operations that are not present in vertical or even deviated systems. Gravity pulls the metal drill pipes, drill collars, drill bit and tools against the well bore wall, causing friction while drilling. In extended-reach wells (ERWs), well bore collapses, stress fracturing and breaking of long drill strings, poor fluid circulation along the length of the well bore, and solids accumulation can trap a drill string in a well bore. Halting the rotation of the drill string further exacerbates friction.
When a drill string becomes stuck, increasing drill fluid circulation can sometimes free the string. Increasing the drilling fluid circulation rate provides fluid lift to the drill string and erodes accumulated solids that choke the hole, both suspending and conveying them to the surface. Drilling fluid is introduced from the surface, flows through the internal fluid conduit of the drill string down to the distal end of the drill string, passes from the drill string, and flows back to the surface through the well bore annulus. The well bore annulus is the space between the drill string and the wall of the well bore. Introducing fluid first into the well bore annulus reverses the flow to and from the surface.
Potentially a number of problems exist with simply increasing drilling fluid flow in a horizontal well, especially an ERW to treat a well bore condition. The fluid exiting the end of the drill string has traveled hundreds or thousands of meters—in some cases several kilometers—before passing into the well bore. To address the problem, the fluid then has to travel possibly thousands of more meters in the well bore annulus before encountering the well bore condition. Some ERWs have horizontal runs beyond 35,000 feet. This requires a tremendous amount of energy to reach this problem site, usually in the form of higher fluid pressure. Well bore conditions, including pore pressure and fracture gradient, can severely limit the maximum pressure of the drilling fluid passing from the drill pipe against the face of the distal end of the well bore. Directly applying fluid to or at least introducing it proximate to the problem area may prevent this situation.
Rarely is there any data or information proximate to where the problem occurs in the well bore. If a collapsed portion of the well bore or trapped part of the drill string is uphole from the borehole assembly (BHA), sensors on the BHA are effectively useless. Having sensing nodes along the operative length of the drill string can provide critical downhole condition information. Such information can permit the determination of borehole conditions in situations such that an operator can act to free the trapped drill string in, a timely and safe manner or respond to a process anomaly, including a kick.
During a well bore collapse or a prolonged cessation of fluid flow, solids accumulation may not permit the re-establishment of fluid flow. Traditional mud-pulsing telemetry does not function when fluid flow is not established. Other means of communication not based upon fluid flow technology is useful in situations where there is loss of drill string or well bore control and well bore fluid flow is not consistent or reliable.